Liquid crystal composition and liquid crystal light modulating apparatus

Abstract

A chiral nematic liquid crystal composition that exhibits a cholesteric phase, said chiral nematic crystal composition comprising 55 wt % to 90 wt % of a nematic liquid crystal composition that comprises, as main components thereof, a liquid crystal ester compound and a liquid crystal pyrimidine compound, wherein said liquid crystal ester compound does not include a tolan skeleton therein and said liquid crystal pyrimidine compound includes a fluorine atom therein; and 10 wt % to 45 wt % of at least one chiral agent. A liquid crystal light modulating apparatus comprising a pair of substrates at least one of which is transparent; and the chiral nematic liquid crystal composition disposed between the substrates.

What is claimed is:  
     
       1. A chiral nematic liquid crystal composition that exhibits a cholesteric phase, said chiral nematic crystal composition comprising: 
       55 wt % to 90 wt % of a nematic liquid crystal composition that comprises, as main components thereof, a liquid crystal ester compound and a liquid crystal pyrimidine compound, wherein said liquid crystal ester compound does not include a tolan skeleton therein and said liquid crystal pyrimidine compound includes one or more fluorine atoms therein; and  
       10 wt % to 45 wt % of at least one chiral agent.  
     
     
       2. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein a total amount of the liquid crystal ester compound which does not include a tolan skeleton and the liquid crystal pyrimidine compound which includes one or more fluorine atoms is at least 45 wt % of a total amount of the nematic liquid crystal composition. 
     
     
       3. A chiral nematic liquid crystal composition as claimed in  claim 2 , wherein the total amount of the liquid crystal ester compound which does not include a tolan skeleton and the liquid crystal pyrimidine compound which includes one or more fluorine atoms is at least 50 wt % of the total amount of the nematic liquid crystal composition. 
     
     
       4. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein the nematic liquid crystal composition further comprises at least one of a liquid crystal biphenyl compound, a liquid crystal phenylcyclohexane compound, a liquid crystal tolan compound and a liquid crystal terphenyl compound. 
     
     
       5. A chiral nematic liquid crystal composition as claimed in  claim 4 , wherein each amount of at least one of the liquid crystal biphenyl compound, liquid crystal phenylcyclohexane compound, liquid crystal tolan compound and liquid crystal terphenyl compound is in a range from 10 wt % to 55 wt % of a total amount of the nematic liquid crystal composition. 
     
     
       6. A chiral nematic liquid crystal composition as claimed in  claim 4 , wherein each amount of at least one of the liquid crystal biphenyl compound, liquid crystal phenylcyclohexane compound, liquid crystal tolan compound and liquid crystal terphenyl compound is at most 50 wt % of a total amount of the nematic liquid crystal composition. 
     
     
       7. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein the liquid crystal ester compound includes at least one of a fluorine group, a chlorine group and a cyano group. 
     
     
       8. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein an amount of each of the liquid crystal ester compound and the liquid crystal pyrimidine compound is in a range from 15 wt % to 85 wt % of a total amount of the nematic liquid crystal composition. 
     
     
       9. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein the chiral agent comprises at least two kinds of chiral agents. 
     
     
       10. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein the liquid crystal ester compound includes a fluorine atom therein. 
     
     
       11. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein the liquid crystal ester compound has a fomula expressed by one of following formulae:                    
       wherein each of “R 1 ” and “R 2 ” is a cyano group or an alkyl group represented by —C n H 2n+1  wherein “n” is an integer of 2 to 10, “X” is a halogen atom or a hydrogen atom, each of “a” and “b” is an integer of 0, 1 or 2, provided that “a” and “b” can not be 0 at the same time.  
     
     
       12. A chiral nematic liquid crystal composition as claimed in  claim 1 , wherein the liquid crystal pyrimidine compound has a following formula:                    
       wherein each of “A” and “A” is a single bond or a phenylene group, provided that they can not be a phenylene group at the same time, each of “X 1 ” and “X 2 ” is a fluorine atom or a hydrogen atom, provided that they can not be a hydrogen atom at the same time, and “n” is an integer of 2 to 10.  
     
     
       13. A liquid crystal light modulating apparatus comprising: 
       a pair of substrates at least one of which is transparent; and  
       a chiral nematic liquid crystal composition as claimed in  claim 1  disposed between the substrates.  
     
     
       14. A liquid crystal light modulating apparatus as claimed in  claim 13 , wherein at least one of the substrates is made of a resin. 
     
     
       15. A liquid crystal light modulating apparatus as claimed in  claim 13  which further comprises a drive unit for applying a drive voltage to the chiral nematic liquid crystal composition, the drive voltage being at most 40V. 
     
     
       16. A liquid crystal light modulating apparatus as claimed in  claim 13 , wherein no resin network structure is provided between the substrates. 
     
     
       17. A liquid crystal light modulating apparatus as claimed in  claim 16 , wherein a plurality of resin nodules are provided between the substrates. 
     
     
       18. A liquid crystal light modulating apparatus as claimed in  claim 17 , wherein the resin nodules form column structures connecting the substrates to each other. 
     
     
       19. A liquid crystal light modulating apparatus as claimed in  claim 17 , wherein the resin nodules form rib structures each extending from one of the substrates and being terminated at an intermediate of a gap between the substrates. 
     
     
       20. A liquid crystal light modulating apparatus as claimed in  claim 13 , wherein the chiral nematic liquid crystal composition achieves a memory effect. 
     
     
       21. A liquid crystal light modulating apparatus as claimed in  claim 13 , wherein the pair of substrates and the chiral nematic liquid crystal composition form a liquid crystal light modulating unit, and wherein the liquid crystal light modulating apparatus comprises a plurality of the liquid crystal light modulating units layered on each other. 
     
     
       22. A chiral nematic liquid crystal composition as claimed in  claim 12 , wherein “X 1 ” and “X 2 ” are both a fluorine atom. 
     
     
       23. A chiral nematic liquid crystal composition as claimed in  claim 12 , wherein one of “X 1 ” and “X 2 ” is a fluorine atom and the other is a hydrogen atom.